Thermally operated vapor valve



Feb. 10, 1959 J. G. DORWARD, JR 2,873,375

THERMALLY OPERATED VAPOR VALVE Filed Feb. 14, 1946 SSheets-Shget 1 INVENTOR. /0/7/? 6 flarward/n Maw Feb. 10, 1959 J. G. DORWARD, JR 2,

THERMALLY OPERATED VAPOR VALVE Filed Feb. 14, 1946 I 5 Sheets-Sheet 2Fig.2 BY

Feb- 1 1 J. G. DORWARD, JR

THERMALLY OPERATED VAPOR VALVE Filed Feb. 14, 1946 3 Sheets-Sheet 5 V IN VEN TOR.

/0/7/? 0- DorwaroC/n United States Patent '0 THERMALLY OPERATED VAPORVALVE Application February 14, .1946, SerialNo. 647,438

Claims. (Cl. ZED-41.9)

This invention relates to the portion of an ionizing mechanism pertinentto the supply and control of vapor to be ionized, and is especiallyconcerned with an ionizing mechanism sometimes termed a calutron, anexample thereof being disclosed in U. S. Patent No. 2,709,222, whichissued to Ernest 0. Lawrence on May 24, i955.

One of the important factors in operating a calutron is the regulationof the rate of ionization of the material being processed. The usualmanner of ionizing. the process material is to pass it in a gaseous formthrough or into the vicinity of an electric are within a magnetic field,so that interaction between the arc and the gas results in theproduction of a quantity of ions-of the gaseous material.

Means are customarily provided for maintaining the arc in as steadyoperation as possible, preferably close to its optimum ionizingcondition. It appears that one of the important influences upon theoperation of the arc is the rate of supply of vapor or gas forionization. This is a sufiiciently critical factor that many expedientshave been resorted to in orderto regulate the steadiness of the arc asaccurately as possible.

Several schemes for regulating the vapor flow have been proposed andtried, but up to the time of the present invention no readilyresponsive, critically accurate and simple arrangement has presenteditself. This is partly due to the fact that all of the mechanismreferred to operates Within a vacuum of about 10- "millimeters ofmercury, and any controlling devices that are mechanically actuated mustsomehow pass through the wall of the tank, giving rise to problems ofsealing, leakage prevention, and maintenance.

It is therefore an object of the invention to provide a means ofaccurately controlling the steadiness of an arc in a calutron.

Another object of the invention is to-provide means for accuratelycontrolling vapor or gas flow in a calutron.

An additional object of the invention is to provide a means, readilyregulable from the exterior ofthe vacuum tank, for controlling vaporflow in a calutron.

' A still further object of the invention is to provide means quicklyresponsive to regulatory changes for controlling vaportlow in acalu'tron.

A still further object of the invention is to provide means foraccurately co'ntrollingfluid flow in any fluidflow system.

Another object of the invention is to provide a valve actuating deviceeffective Within a vacuum tank without the transmission of mechanicalmotion through the wall of the tank.

A still further object of the invention is, in general, to improve valvemechanisms.

A further object of the invention is, in general, to improve calutrons,

Other objects, together with the foregoing, appear from the followingdescription o'f on'e embodiment of the in 2 vention, such embodimentbeing illustrated in the accompanying drawings, in which:

Figure 1 is a cross section on a generally vertical plane of afragmentary portion of a calutron, the section for the most part beingon a median plane to illustrate the internal construction of a calutronsource unit incorporating the valve of the invention;

Figure 2 is a cross section on the same plane as Figure l, but showingto an enlarged scale the charge heating chamber, charge bottle, andvapor valve of the invention. Figure 3 is across section, the :plane ofwhich is indicated by the line 3-3 of Figure 2;

Figure 4 is a cross section on the same plane as that of Figures 1 and2, showing to a greatly enlarged scale the valve head, valveseat, andtheir immediate environment.

For a'd'etailed description of a calutron of the general type shownherein in fragmentary form, reference is bad to the above-identifiedpatent of Lawrence. Briefly, however, 'and as illustrated herein, thesource portion of such a calutron is for disposition within a magneticfield existing between the poles 6 and 7 of an electromagnet. In thisregion there is situated an evacuated chamber 8, largely defined by anupper wall 9, a lower wall 11, and a face plate 12. The pressure withinthe chamber 8 is established and-maintained by a suitable evacuatingmechanism, not shown. At a suitable point within the chamher there isdisposed an ionizing mechanism, generally designated 13. The specificionizing mechanism is not of consequence to the current invention, sothat a generally exemplary form is disclosed. This structure iscustomarily referred to as a source unit. It involves a mounting 16,appropriately secured'to the face plate 12 and carrying a stem 17through which a number of sup: ports 18 and leads 19 extend. Thesesupports and leads are not illustrated in detail herein, as they areapart of the general calutronmechanism not directly concerned with thecurrent disclosure.

Within the chamber 8, the face plate 12 is supplied with a bracket 21supporting an insulator 22, on which is fastened a mounting arm 23. Onthe mounting arm is disposed a source block 24, incorporating a chargecavity 26 in communication through avapor passage 27 with a gasdistributionchamber 2 8, also formed Within the charge block 24.. Thedistribution chamber'leads to an arc cavity 2.9 provided with an arcopeningfii opposite accelerating electrodes 32, arranged in thecustomary fashion. In the present instance, the arc block 24 itselfserves as an anode for antarc that is established between the arc blockand. a filamentary cathode 33 disposed at the inner end of a cathodestern 3d passing through the mounting 16 and provided with appropriatehermetic seals.

In the customary operation of this mechanism, vapor from the chamber 26flows through the passage 27 and through the distribution chamber 28into the arc cavity 29. 'An electric are extending through such cavity'between the blockanode 24 and the cathode 33 is effective partially toionize the'passing vapor. The ions are withdrawn with the assistance ofthe accelerating electrodes 32. It is the control of the vapor passingfrom the chamber 26 to the are within the cavity 25? that is ofconsequence in the present'circumstance. Tocontrol the rate of flow ofsuch vapor and thereby to regulate the functioning of the are all inaccordance with the present invention, there is provided a valve in thenature of a poppet valve.

One end of thechamber 26 is closed by a removable cover 36, preferablyof arr-electrically conducting material such as .metal, .in goodelectrical contact, when in closed position, with the material of thesource block so that a ground or electric connection on the sourceblock. is effective to include the cover 36 in the same circuit,

Secured to and depending from the cover 36 is a metallic tube 37,disposed substantially coaxially with the walls of the chamber 26 andextending for nearly, but not quite, the entire length of such chamber.The tube 3'7 itself is of thermally conducting material, such as ametal, having a well-known coefiicient of thermal expansion. Preferably,the tube 37 acts as an anchor or support for a charge bottle 38containing the material to be processed or vaporized. To this end, thetube 37 is extended by a flange 39 carrying a plurality of fasteners 41,also engaging an annular end 42 of the charge bottle 38. The end 42 issuitably sealed to a circular, cylindrical charge bottle body 43, itselfcarrying an internally threaded head 44. A plug 46 is threaded into, thehead 44 and is readily removable to afford access to the interior of thecharge bottle 38.

While it may not be necessary in the event the charge is of a liquid orgaseous form under normal conditions, it is still advisable to have somemeans for positioning a pulverulent charge material away from theimmediate vicinity of the end of the valve tube 37. For that reason,there is clamped between the flange 39 and the end 42 an intermediatecollar 47, held in place by the fastenings 41 and carrying a depending,foraminous, circular cylindrical tube 48, at its free end closed by aforaminous disk 49, thus forming a thimble completely protecting thedepending tube 37 from the contents of the charge bottle 38 until orunless such contents are in liquid or gaseous form.

In accordance with the usual practice, the contents of the charge bottle38 are converted from a solid, granular, or pulverulent form into avapor or gaseous form by heat. In the present instance, the source block24, especially as shown in Figure 3,-is provided with an electricallyenergized heating coil 51, effective to transmit heat to theencompassing material of the source block, from whence it is transferredto the contents of the charge bottle 38 in a suflicient amount to give,rise to the generation of gas or vapor within the charge bottle and totend to cause flow through the foraminous tube 48.

In accordance with the present invention, the flow of gas from thecharge bottle is precisely regulated by a poppet valve, generallydesignated 53. This valve includes a valve seat 54, formed at theterminus of the tube 37, with which cooperates a poppet valve head 56 oftruncated, conical form, adapted to move axially relative to the valveseat 54. When the valve head 56 approaches the valve seat 54, it reducesthe area available for flow therebetween until such time as the headabuts the valve seat 54, whereupon flow therebetween is completelyinterrupted. As the valve head moves away from the seat, the areaavailable for gas flow is increased and the flow likewise increases insome proportion thereto.

The valve head 56 is positioned with respect to the seat 54 by a valvestem, generally designated 57. This is made up of a theaded ferrule 58,screwed into the valve head 56 and capping the terminus of a stem tube59, fabricated of a material, such as a metal, having a wellknownthermal expansion coeflicient, and effective readily to transmit heat.The stem tube 59 extends coaxially through the tube 37 and is fastenedthereto at one end by a sleeve and jam nut assembly 61.

Particularly in accordance with the present invention, there is provided'a means for supplying heat to the thermally-responsive valve stem 57.For this reason, there is located within the tube 59 a helix of electricheating wire 62, at one end jammed between the tube 59 and the ferrule58 for good electrical contact therewith and at its other end united toa conducting stem 63 passing through an insulating disk 64 and connectedto an electric conductor 66, in turn passing through the supportingmechanisn 17 to the exterior of the structure. To assist in maintainingelectrical isolation between the aerasvs coil 62 and the conducting tube59, the tube is filled with an insulating powder 67.

In this fashion, it is possible, by including the source block 24 andthe conductor 66 in the same circuit, to establish a regulated currentflow through the heating coil 62, and by varying the current flow tovary the temperature of the coil and thereby the temperature of the stem57. If the temperature of the stem is changed to or maintained at somepredetermined value with respect to the temperature of the tube 37, adifierential motion or spacing between the valve head 56 and the valveseat 54 is thermally induced, so that the annular orifice for gas flowbetween the valve head andseat is then a function of the current flowingin the electrical heating circuit. It then becomes a simple matter, byaltering the current flow in the heating circuit, to alter the vaporflow through the tube 37.

It is to be remembered that when the valve 53 is opened there is a gasflow through the tube 37 and along the stem 57, and that the temperatureof the flowing gas or vapor is somewhat less than the temperatureinduced in the stem 57 by the interior electric heater. Thus to maintainsteady conditions it is necessary, since heat is at all times beingcarried away from the stem 57, to make up at least the loss of heat bysupplying additional heat through the heating coil 62. The rate at whichheat is supplied to the vapor from the stem does not sensibly orimportantly change the temperature of the vapor from the aspect of theremaining processing, but is sufficient to promptly reduce thetemperature of the stem 57 so that upon reduction or interruption of thecurrent supply to the heating coil 62, the valve head 56 very promptlyapproaches the valve seat 54, and quickly produces a correspondingchange in the vapor flow to the are.

In accordance with the invention, therefore, there is provided a meansreadily regulable from the exterior of the vacuum tank, withoutmechanical transmission of force, for the quick and accurate control ofthe ionizing are by a corresponding control of gas flow thereto. Theresult is to produce an effective way of carefully regulating theoperation of an ionizing mechanism, such as a calutron, and to produce ageneral improvement in the operation of the structure.

What is claimed is:

1. A caultron comprising a charge bottle, a tube secured to andextending into said charge bottle, a valve seat on said tube, a valvehead adapted to cooperate with said seat, a valve stem secured to saidtube and to said valve head, and means for thermally varying the lengthof said stem to regulate the relative position of said valve head andsaid valve seat to control the fiow of charge from said charge bottle.

2. A calutron comprising a charge heating chamber, a charge bottlefitting within said chamber, said bottle being adapted to contain acharge convertible to vapor by the heat from said heating chamber, athermally-responsive valve for controlling the efiiux of said vapor fromsaid bottle, and an individually controllable heating means forenergizing said thermally-responsive valve. 3. A calutron comprising acharge bottle adapted to contain a grannular charge material, aforaminous thimble disposed within said charge bottle for defining acentral charge-free cavity therein, a vapor-conducting tube extendinginto said cavity, said tube being provided with a valve seat, a valvehead adapted to cooperate with said seat, a thermally-responsive stemsecured to said valve head passing through said tube and securedthereto, and means for heating said stem to produce diiferentialmovement of said valve head and said valve seat to control the How ofsaid vapor from said charge bottle.

4. A calutron comprising a charge bottle adapted to contain a chargeconvertible to vapor by the application of heat thereto, athermally-responsive valve for controlling the efliux of said vapor fromsaid bottle, and heating means controllable separately from theapplication of 5 heat to said charge for energizing saidthermally-respom sive valve.

5. A calutron comprising a closed tank having a wall, means forevacuating said tank, a source of vapor within said tank, means withinsaid tank for ionizing said vapor, means within said tank forconductingvapor from said source to said ionizing means, a valve within said tankfor controlling flow through said conducting means, thermally-responsivemeans within said tank for actuating said valve, an electric heaterwithin said tank for supplying heat to said thermally-responsive means,and electric References Cited in the file of this patent UNITED STATESPATENTS 1,697,432 Martin Jan. 1, 1929 2,341,551 Hoover Feb. 15, 19442,597,653 Smith May 16, 1950

